Subject: Re: [PATCH v2 08/15] unpack-trees: don't respect submodule.update

From: Junio C Hamano <[email-masked]>
Date: Thu, 03 Aug 2017 13:37:10 -0700

Brandon Williams <[email-masked]> writes:

> The 'submodule.update' config was historically used and respected by the
> 'submodule update' command because update handled a variety of different
> ways it updated a submodule.  As we begin teaching other commands about
> submodules it makes more sense for the different settings of
> 'submodule.update' to be handled by the individual commands themselves
> (checkout, rebase, merge, etc) so it shouldn't be respected by the
> native checkout command.

Soooo... what's the externally observable effect of this change?  Is
it something that can be illustrated in a set of new tests?

IOW does this commit by itself want to change the behaviour of
"submodule update" and existing (indirect) users of unpack-trees?
Or does it want to keep the documented behaviour of "submodule
update" while correcting unintended triggering in other (indirect)
users of unpack-trees of the same machinery that is being removed in
this patch?

> -	switch (sub->update_strategy.type) {
> -	case SM_UPDATE_UNSPECIFIED:
> -	case SM_UPDATE_CHECKOUT:
> -		if (submodule_move_head(ce->name, old_id, new_id, flags))
> -			return o->gently ? -1 :
> -				add_rejected_path(o, ERROR_WOULD_LOSE_SUBMODULE, ce->name);
> -		return 0;
> -	case SM_UPDATE_NONE:
> -		return 0;
> -	case SM_UPDATE_REBASE:
> -	case SM_UPDATE_MERGE:
> -	case SM_UPDATE_COMMAND:
> -	default:
> -		warning(_("submodule update strategy not supported for submodule '%s'"), ce->name);
> -		return -1;
> -	}
> +	if (submodule_move_head(ce->name, old_id, new_id, flags))
> +		return o->gently ? -1 :
> +				   add_rejected_path(o, ERROR_WOULD_LOSE_SUBMODULE, ce->name);
> +	return 0;

With this update, we always behave as if update_strategy.type were
either left unspecified or explicitly set to checkout.  Other arms
in this switch (and the other switch too), especially "none", were
not expecting a call to submodule_move_head() to be made, but now
the call is unconditional.

>  }
>  
>  static void reload_gitmodules_file(struct index_state *index,
> @@ -293,7 +282,6 @@ static void reload_gitmodules_file(struct index_state *index,
>  				submodule_free();
>  				checkout_entry(ce, state, NULL);
>  				gitmodules_config();
> -				git_config(submodule_config, NULL);
>  			} else
>  				break;
>  		}
> @@ -308,19 +296,9 @@ static void unlink_entry(const struct cache_entry *ce)
>  {
>  	const struct submodule *sub = submodule_from_ce(ce);
>  	if (sub) {
> -		switch (sub->update_strategy.type) {
> -		case SM_UPDATE_UNSPECIFIED:
> -		case SM_UPDATE_CHECKOUT:
> -		case SM_UPDATE_REBASE:
> -		case SM_UPDATE_MERGE:
> -			/* state.force is set at the caller. */
> -			submodule_move_head(ce->name, "HEAD", NULL,
> -					    SUBMODULE_MOVE_HEAD_FORCE);
> -			break;
> -		case SM_UPDATE_NONE:
> -		case SM_UPDATE_COMMAND:
> -			return; /* Do not touch the submodule. */
> -		}
> +		/* state.force is set at the caller. */
> +		submodule_move_head(ce->name, "HEAD", NULL,
> +				    SUBMODULE_MOVE_HEAD_FORCE);
>  	}
>  	if (!check_leading_path(ce->name, ce_namelen(ce)))
>  		return;